Default open differential control switch

ABSTRACT

A vehicle is described having plural modes of operation for the front and rear differential and whereupon start-up of the vehicle, the front and rear differentials are opened to their most open position.

PRIORITY

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 13/325,561 titled DEFAULT OPEN DIFFERENTIALCONTROL SWITCH filed Dec. 14, 2011 which is a non-provisionalapplication of U.S. Provisional Patent Application Ser. No. 61/423,915titled DEFAULT OPEN DIFFERENTIAL CONTROL SWITCH filed Dec. 16, 2010. Thedisclosures of which are expressly incorporated herein by reference.

BACKGROUND

The subject disclosure relates to an all terrain vehicle, and moreparticularly to one having a default setting for the front and reardifferentials.

Oftentimes, all terrain vehicles have front and rear differentialscoupled to a transmission, with multiple settings of the differentialson the vehicle, between: rear differential disengaged, differentialengaged with both rear wheels locked or with limited slip, or bothdifferentials engaged and locked. Multiple riders may have access to thevehicles, with no awareness of the present state of the differentials.

SUMMARY

In one embodiment described herein, a vehicle comprises a frame; frontand rear ground engaging members supporting the frame; a propulsion unitsupported by the frame; a transmission motively coupled to thepropulsion unit; a front differential coupled to the transmission and tothe front ground engaging members; a rear differential coupled to thetransmission and to the rear ground engaging members; where the frontand rear differentials are selectively locked or unlocked to providevarious performance modes for the vehicle, and the front and reardifferentials being controllably unlocked upon a certain vehicle signal.

In another embodiment described herein, a motor vehicle having amultimode traction system is described. The vehicle comprises a pair ofrear wheels and a pair of steerable front wheels. A propulsion unit isprovided for generating torque to drive the wheels, and a control unitincludes programming therein for operating the propulsion unit. A reardifferential is operatively connected with a rear drive train andsupplying torque from the propulsion unit to the rear wheels, the reardifferential including a lock for locking the rear differential. A frontdifferential is operatively connected within a front drive train andselectively supplies torque from the propulsion unit to the frontwheels, the front differential including a lock for locking the frontdifferential. An ignition switch is electrically coupled to the controlunit, the ignition switch having a first position and a second position;the ignition switch causing a first signal to be sent to the controlunit when the ignition switch is moved from the second position to thefirst position, the ignition switch causing a second signal to be sentto the control unit when the ignition switch is moved from the secondposition to the first position; wherein the control unit responds toreceiving the first signal by emitting signals to cause unlocking ofboth the front and rear differentials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a utility vehicle of the subjectdisclosure;

FIG. 2 is a rear perspective view of a utility vehicle according to thepresent disclosure;

FIG. 3 is a left side view of the vehicle of FIG. 1;

FIG. 4 is a rear side view of the vehicle of FIG. 1;

FIG. 5 is a front perspective view of a straddle-type vehicle of thepresent disclosure;

FIG. 6 is a left side view of the vehicle of FIG. 5;

FIG. 7 is a right side view of the vehicle of FIG. 5;

FIG. 8 is a front view of the vehicle of FIG. 5;

FIG. 9 is a schematic of the drivetrain of the present disclosure;

FIG. 10 is a flow chart of the operation of the vehicle;

FIGS. 11A-11C show a first embodiment of the actuator device; and

FIGS. 12A-12D show a second embodiment of the actuator device.

DETAILED DESCRIPTION OF THE EMBODIMENT

With reference first to FIG. 1, an all terrain vehicle is shown at 2 inthe form of a side-by-side vehicle. Vehicle 2 generally includes a frame4 supported by front and rear ground engaging members 6, 8, comprised offront wheels 10, front tires 12, and rear wheels 14 and rear tires 16.Front ground engaging members 6 are attached to frame 4 by way ofsuspension 20 whereas rear ground engaging members 8 are attached toframe 4 by way of suspension 22. An operator's area is defined in thecenter of the vehicle and shown generally at 30. Operator's area iscomprised of side-by-side seats 32 which are coupled to frame 4 as knownin the art. As shown in FIGS. 2 and 3, operator's area 30 furthercomprises operation controls in the form of steering wheel 36,accelerator pedal 38, brake pedal 40, instrument cluster 42 andtransmission shift lever 44.

With reference now to FIGS. 3 and 4, vehicle 2 includes a propulsionunit 50 and a transmission unit 60 (FIG. 3) including a continuouslyvariable transmission (CVT) as described herein. As vehicle 2 is a fourwheel drive or all wheel drive unit, vehicle 2 would include a front andrear differential as described herein coupled to engine 50 andtransmission 60 for propelling the front and rear ground engagingmembers 6, 8. The construction of the drivetrain could be similar tothat shown in U.S. Pat. No. 7,819,220, the subject matter of which isincorporated herein by reference.

With reference now to FIGS. 5-8, the vehicle could be in the form of astraddle-type vehicle as shown at 102 having a frame 104 (FIG. 6) andfront and rear ground engaging members 106, 108 defined by wheels 110,tires 112 and wheels 114 and tires 116. Vehicle 102 further includes afront suspension 120 and a rear suspension 122 (FIG. 6). Operator's area130 is comprised of straddle seat 132, a steering mechanism in the formof handlebars 136, an accelerator in the form of a pull lever 138 (FIG.7), at least one brake mechanism in the form of a lever 140 (FIG. 5),instrument cluster 142, and a transmission shift lever 144 (FIG. 7). Inaddition, vehicle 102 includes propulsion unit 150 and transmission 160(FIG. 6). In a like manner to vehicle 2, vehicle 102 is a four wheeldrive or all wheel drive vehicle having a front and rear differential asdescribed herein. The construction of the drivetrain of vehicle 102could be similar to that shown and described in U.S. Pat. No. 7,845,452,the subject matter of which is incorporated herein by reference.

In one embodiment, propulsion unit 50 or 150 is a typical combustionengine, but could also comprise a multifuel engine capable of utilizingvarious fuels. Exemplary engines are disclosed in U.S. patentapplication Ser. No. 11/445,731, filed Jun. 2, 2006, the disclosure ofwhich is expressly incorporated by reference herein. In anotherembodiment, engine 50/150 is a hybrid electric engine, while in anotherembodiment, engine 50/150 is a hybrid electric drive engine. Inaddition, the propulsion unit need not have an engine at all, but couldbe all electric, for example similar to that disclosed in U.S. patentapplication Ser. Nos. 12/484,921, 12/816,0004, 12/816,095, 12/816,052,or 12/815,907, the subject matter of which is incorporated herein byreference.

With reference now to FIG. 9, the drivetrain of vehicle 2 (or 102) willbe described in greater detail, and is described as including an engine.In one embodiment, transmission 60 or 160 includes a shiftabletransmission 62 and a continuously variable transmission (“CVT”) 64. CVT64 is coupled to engine 50 and shiftable transmission 62. Shiftabletransmission 62 is coupled to drive shaft 66 which in turn is coupled tofront differential 68 and to drive shaft 70 coupled to rear differential72.

Shiftable transmission 62 is shiftable between a high gear for normalforward driving, a low gear for towing, a reverse gear for driving inreverse, and a park setting which locks the output drive of theshiftable transmission from rotating. Exemplary shiftable transmissionsand CVTs are disclosed in U.S. Pat. No. 6,725,962 and U.S. Pat. No.6,978,857, the disclosures of which are expressly incorporated byreference herein.

The operation of engine 50 and transmission 60 is controlled through anoperator input 74 (such as transmission control 44 or as furtherdescribed herein) and an electrical control module (“ECM”) 76. ECM 76has software to control the operation of engine 50 and transmission 60based on operator inputs 74, and sensors which monitor engine 50 andsoftware to control the operation of differentials 68 and 72. It shouldbe understood that differential 68 is interconnected to wheels 10 by wayof front stub shafts 80, and that rear differential 72 is coupled torear wheels 14 by way of rear stub shafts 82. It should be furtherappreciated that the front wheels and rear wheels include brakes 84 and86.

Various configurations of front differential 68 and rear differential 72are contemplated. Regarding front differential 68, in one embodimentfront differential 68 has a first configuration wherein power isprovided to both of the wheels of front axle 80 and a secondconfiguration wherein power is provided to one of the wheels of axle 80,such as the wheel having the less resistance relative to the ground.

In one embodiment, front differential 68 may also include active descentcontrol (“ADC”). ADC is an all wheel drive system that provideson-demand torque transfer to the front wheels with a front drive and isalso capable of providing engine braking torque to the front wheels witha back drive. Both the front drive and the back drive are portions offront differential 68 and may be active or inactive. In the case of thefront drive, when active, power is provided to both of the wheels offront axle 80 and, when inactive, power is provided to one of the wheelsof front axle 80. In the case of the back drive, when active, enginebraking is provided to the wheels of front axle 80 and, when inactive,engine braking is not provided to the wheels of front axle 80.

Regarding rear differential 72, in one embodiment rear differential 72is a locked differential wherein power is provided to both of the wheelsof axle 82, rear differential 72 may be a lockable/unlockabledifferential relative to output shafts 82. When rear differential 72 isin a locked configuration power is provided to both wheels of axle 82.When rear differential 72 is in an unlocked configuration, power isprovided to one of the wheels of axle 82, such as the wheel having theless resistance relative to the ground. Front and rear brakes 80, 82 areconnected to front and rear wheels 10, 14 as is known in the art. Aparking brake 88 may also be connected in drive shaft 70.

It is contemplated that the front differential 68 and rear differential72 are spring-loaded dog clutches which are solenoid operated. Whenpower is applied to the solenoid, the clutches are opened whereas whenthe power is turned off to the solenoid, the clutches are spring biasedto lock up. Sensors 90 and 92 monitor the condition of the differentials68 and 72 which in the present embodiment sends the power to thedifferential clutch solenoids. With reference now to FIG. 10, theoperation of the vehicle and the differentials will be described ingreater detail.

As shown in step 200, an operator would turn an ignition key into thefirst or “On” position which first causes logic in the ECM 76 to beuploaded, see step 202. At step 204, sensors 90 and 92 are read todetermine the condition and position of the front 68 and rear 72differentials. At step 206, the condition of the front and reardifferentials is determined by querying whether the front and reardifferential are open and unlocked. If they are not, step 208 isactivated providing a signal to the differential solenoids to open thespring-loaded clutches as described above. As shown in FIG. 10, thevehicle may now be operated at step 210. The ignition switch could havemore than two positions, for example in some vehicles there are threepositions where the third position is to activate the headlights.

Other steps during the operation of the vehicle include step 212 whichqueries whether the vehicle speed is equal to 0 and the parking brakeset, and if yes, step 214 is activated to lock the front and reardifferentials.

In the particular embodiment described, the front and rear differentialsare locked at shutdown when the ignition key is moved to the second and“Off” position, due to the parking brake 88 being positioned withindriveshaft 70. Thus it is preferable to lock the differentials when thevehicle is shut down so that the parking brake 88 properly functionswith a locked driveshaft 70. However on startup, the front and reardifferentials are opened to their most open position as described abovewith reference to FIG. 10. It should be noted that if the parking brakeis not on a drive shaft, that the front and rear differentials could beopened to their most open position at vehicle shut-down.

The differentials could be unlocked by a certain vehicle signal, forexample from the ECU, or the reverse logic could be implemented wherethe default is open and a certain vehicle signal would be required tolock the differentials.

Finally with respect to FIGS. 11A-11C and 12A-12D, the actuation of thedifferential settings will be described. With respect first to FIG. 11A,a three position momentary switch may be provided within instrumentcluster 42 whereby upon initial startup, the default of thedifferentials provides for the rear differential to be in the openposition such that light 242 is illuminated. With respect to FIG. 11B,the momentary switch may be clicked down to illuminate light 244 to showthat the vehicle is in the two wheel drive mode or having the reardifferential locked. With respect to FIG. 11C, the switch 240 may beclicked upwardly with light 246 to show an all wheel drive mode withboth the front and rear differentials locked.

With respect now to FIG. 12A, a second embodiment 250 may be shown witha momentary two position switch 250 a and a momentary three positionswitch 250 b. FIG. 12B shows the two position switch activated settingthe differential and the one wheel drive configuration. FIG. 12C shows aone click down position of the momentary switch 250 b showing the twowheel drive mode and FIG. 12D shows the one click up mode of momentaryswitch 250 b showing the all wheel drive mode.

The invention claimed is:
 1. A vehicle, comprising: a frame; front andrear ground engaging members supporting the frame; a propulsion unitsupported by the frame; a transmission motively coupled to thepropulsion unit; at least one differential selected from 1) a frontdifferential driven by the transmission and driving the front groundengaging members and 2) a rear differential driven by the transmissionand driving the rear ground engaging members; an electronic enginecontrol unit for operating the propulsion unit; the at least onedifferential being selectively locked or unlocked to provide variousperformance modes for the vehicle responsive to signals received fromthe electronic engine control unit; a differential switch having aplurality of states, each state corresponding to a setting of at theleast one differential, the differential switch in communication withthe electronic engine control unit; an ignition, the at least onedifferential being controllably locked or unlocked by the engine controlunit responsive to a first signal indicative of a change in the state ofthe ignition, the engine control unit controlling the at least onedifferential responsive to the first signal regardless of a setting ofthe differential switch.
 2. The vehicle of claim 1, wherein the at leastone differential is locked responsive to an indication that the state ofthe ignition switch is changed to an “off” state.
 3. The vehicle ofclaim 1, wherein the at least one differential is unlocked responsive toan indication that the state of the ignition switch is changed from an“off” state to an “on” state.
 4. The vehicle of claim 1, wherein a firstperformance mode is invoked responsive to one of vehicle startup andvehicle shutdown.
 5. The vehicle of claim 4, wherein the at least onedifferential is locked responsive to vehicle shutdown.
 6. The vehicle ofclaim 4, wherein the at least one differential is unlocked responsive tovehicle startup.
 7. The vehicle of claim 1, wherein the at least onedifferential includes the front differential and the rear differential.8. The vehicle of claim 1, wherein the electronic engine controlcontains programming therein that dictates at least one setting of theat least one differential.
 9. The vehicle of claim 1, wherein theelectronic control unit interprets the first signal to override anysetting indicated by the differential switch.
 10. A vehicle, comprising:a frame; front and rear ground engaging members; a propulsion unitsupported by the frame; a transmission motively coupled to thepropulsion unit; at least one differential selected from 1) a frontdifferential driven by the transmission and driving the front groundengaging member and 2) a rear differential driven by the transmissionand driving the rear ground engaging member; a differential switchhaving first and second states that call for first and second states ofthe at least one differential; the vehicle having an operational modeand a non-operational mode; the vehicle providing that responsive to thevehicle being put in the operational mode, the at least one differentialis unlocked, regardless of the current state of the differential switch.11. The vehicle of claim 10, further comprising an ignition having an onmode, wherein placing the ignition in the on mode causes unlocking ofthe at least one differential.
 12. The vehicle of claim 11, whereinplacing the ignition switch into an off mode causes locking of the atleast one differential.
 13. The vehicle of claim 10, wherein the vehiclerequires that the at least one differential is unlocked when the vehicleis placed in the operational mode.
 14. The vehicle of claim 10, furtherincluding a parking brake coupled to the vehicle to provide braking toat least one of the front and rear ground engaging members.
 15. Anelectronic control unit for a motor vehicle including: a differentialcontrol output port; a processor; a differential switch input portoperable to receive differential control signal from a differentialswitch; memory containing instructions that when interpreted by theprocessor cause the processor to: determine when the motor vehicle isplaced in an “on” mode and responsive thereto, provide that an output ofthe differential control output port provides for a differential of thevehicle to assume an unlocked state regardless of any input received viathe differential switch input port.
 16. The control unit of claim 15,wherein the instructions further cause the processor to determine whenthe motor vehicle is switched out of the “on” mode and responsivethereto, provide that an output of the differential control output portprovides for a differential of the vehicle to assume a locked state. 17.The control unit of claim 15, wherein the determination that the motorvehicle is placed in the “on” mode includes a determination that anignition switch is in an “on” mode.
 18. The control unit of claim 15,wherein placement of the motor vehicle in the “on” mode results inunlocking of front and rear differentials.
 19. An electronic controlunit for a motor vehicle including: a differential control output port;a processor; memory containing instructions that when interpreted by theprocessor cause the processor to: determine when the motor vehicle isplaced in an “on” mode and responsive thereto, provide that an output ofthe differential control output port provides for a differential of thevehicle to assume an unlocked state, and permit an output of thedifferential control output port to provide for the differential toassume a locked state after being initially automatically placed intothe unlocked state upon placement of the vehicle into the “on” mode. 20.The control unit of claim 19, wherein the determination that the motorvehicle is placed in the “on” mode includes a determination that anignition is transitioned from an “off” mode to an “on” mode.